SYNTHESIS OF AEI and Cu-AEI ZEOLITES

ABSTRACT

An alkali-free H-AEI zeolite and synthesis procedure are disclosed, as well the use of such zeolite as a catalyst in an SCR process.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/402,687, filed Sep. 30, 2016.

FIELD OF INVENTION

The present invention relates to the synthesis of hydrogen-form (H-form)zeolites having an AEI framework (H-AEI). The invention also relates tosynthesis techniques for such zeolites and their use as a catalyst.

BACKGROUND

Zeolites are porous crystalline or quasi-crystalline aluminosilicatesconstructed of repeating SiO₄ and AlO₄ tetrahedral units. These unitsare linked together to form frameworks having regular intra-crystallinecavities and channels of molecular dimensions. Numerous types ofsynthetic zeolites have been synthesized and each has a unique frameworkbased on the specific arrangement of its tetrahedral units. Byconvention, each framework type is assigned a unique three-letter code(e.g., “AEI”) by the International Zeolite Association (IZA).

Synthetic zeolites are typically produced using a structure directingagent (SDA), also referred to as a “template” or “templating agent”.SDAs are typically complex organic molecules that guide or direct themolecular shape and pattern of the zeolite's framework. Generally, theSDA serves to position hydrated silica and alumina and/or to serve as amold around which the zeolite crystals form. After the crystals areformed, the SDA can be removed from the interior structure of thecrystals, leaving a molecularly porous aluminosilicate cage.

Zeolites have numerous industrial applications including the catalytictreatment of exhaust gas from combustion of hydrocarbon fuels, such asinternal combustion engines, gas turbines, coal-fired power plants, andthe like. To improve catalytic performance, zeolites are frequentlyloaded with a transition metal, such as copper. In one example, a metalloaded zeolite can catalytically reduce the concentration of nitrogenoxides (NO_(x)) in the exhaust gas via a selective catalytic reduction(SCR) process.

AEI zeolite synthesis methods are known. These methods typically requirea source of alkali metal ions, such as Na₂O. Before AEI zeolites can beused as an SCR catalyst, a significant portion of the alkali metal isdesirably removed. It is difficult to completely remove all traces ofalkali metal from the zeolite. Unfortunately, even residual amounts ofsodium in an AEI zeolite can affect the amount of exchanged transitionmetal during catalyst preparation. In addition, at high temperatures(e.g., >800° C.), sodium can interact with the zeolite cage to formsodium-aluminates which, in turn, can collapse the cage structure,thereby reducing the high temperature durability of the zeolite.Accordingly, there is a need for an improved method for producingalkali-free AEI zeolites.

SUMMARY

Applicants have developed a unique series of hydrogen-form zeolites(H-zeolites) which are referred to herein as “JMZ-9 zeolite” or “JMZ-9”.This zeolite material contains the AEI framework structure as theprimary phase and a template (SDA), and is essentially free of metalcations, such as sodium. In contrast to conventional zeolite synthesis,which uses alkali metal ions, it has been found that alkali-free AEIzeolites can be synthesized using a high concentration of one or morehydroxide-form SDAs and preferably using a reactive admixture thatcontains a high concentration of hydroxide-form SDAs relative to theconcentrations of silica and/or alumina.

According to certain aspects of the invention, JMZ-9 is a novelcomposition comprising a synthetic H-form zeolite having an AEIframework structure as the primary crystalline phase, and an SDA,wherein the zeolite is essentially free of metal ions, including bothalkali metal ions and transition metal ions.

These H-form AEI zeolites can undergo further processing to form ametal-loaded zeolite, such as copper-AEI, which can be used as acatalyst. Accordingly, in another aspect of the invention, provided is acatalyst composition comprising a synthetic zeolite having an AEIframework as the primary crystalline phase and a silica-to-alumina ratioof about 10 to about 50, wherein the zeolite has 0.1 to 7 weight percentexchanged transition metal and wherein the zeolite is essentially freeof alkali metal. Preferred transition metals include copper and/or iron.

In another aspect of the invention, provided is a method for producing aH-form AEI zeolite comprising the steps of (a) preparing an admixturecontaining (i) at least one source of alumina, (ii) at least one sourceof silica, and (iii) at least one structure directing agent (SDA) inhydroxide form, wherein the admixture is essentially free of alkalimetals, and optionally is also essentially free of other non-aluminummetal ions; and (b) heating the admixture under autogenous pressure at atemperature and with stirring or mixing for a sufficient time tocrystalize H-form zeolite crystals having an AEI framework. The at leastone SDA preferably includes about 20 to about 100 weight percentN,N-Diethyl-cis-2,6-dimethylpiperidium, based on the total weightpercent of the SDAs. The SDA can contain from about 0 to about 80 weightpercent N,N-Dimethyl-3,5-dimethylpiperidinium, with the balance beingN,N-Diethyl-cis-2,6-dimethylpiperidium.

In another aspect of the invention, provided is a catalyst article fortreating exhaust gas comprising a catalyst composition described herein,wherein the catalyst composition is disposed on and/or within ahoneycomb monolith substrate.

And in yet another aspect of the invention, provided is a method fortreating an exhaust gas comprising contacting a combustion exhaust gascontaining NO_(x) and/or NH₃ with a catalyst article described herein toselectively reduce at least a portion of the NO_(x) into N₂ and H₂Oand/or oxidize at least a portion of the NH₃.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an XRD of calcined alkali-free AEI prepared in example 1.

FIG. 2A shows an SEM of alkali-free AEI (SAR≈30) prepared in example 1.

FIG. 2B shows an SEM of alkali-free AEI (SAR≈30) prepared in example 2.

FIG. 3 shows an SEM of alkali-free AEI (SAR≈30) prepared in example 3.

FIG. 4 shows an SEM of alkali-free AEI (SAR≈30) prepared in example 4.

FIG. 5A shows NOx conversions on 3% Cu.AEI (SAR≈20) and 2.5% Cu.H-AEI(SAR≈30).

FIG. 5B shows N20 selectivity of reference 3% Cu.AEI (SAR≈20) and 2.5%Cu.H-AEI (SAR≈30).

FIG. 5C shows NOx conversions on 3% Cu.AEI (SAR≈20) and one-pot Cu-AEI(Example 5).

FIG. 5D shows N₂O selectivity of reference 3% Cu.AEI (SAR≈20) andone-pot Cu-AEI (Example 5).

FIG. 6 is a diagram showing an AEI-zeolite preparing according to oneaspect of the invention as an SCR and/or ASC catalyst.

DETAILED DESCRIPTION

In general, JMZ-9 zeolites are aluminosilicates having an AEI frameworkstructure in H-form as the primary crystalline phase and an SDA, and areessentially free of metal ions.

As used herein, the term “AEI” refers to an AEI crystalline structure asthat code is recognized by the International Zeolite Association (IZA)Structure Commission. Aluminosilicates zeolites having an AEI frameworkas the primary crystalline phase means that the zeolite crystalcomprises at least about 70 wt. %, at least about 80 wt. %, at leastabout 90 wt. %, at least about 95 wt. %, or at least about 99 wt. %, ofAEI aluminosilicate framework, based on the total weight ofaluminosilicate in the zeolite material. Preferably, any secondarycrystalline phase comprises less than about 10 weight percent of thezeolite material, more preferably less than about 5 weight percent, andeven more preferably less than about 2 weight percent.

As used herein, the term “essentially free of metal ions” means thatalkali, alkaline-earth, and transition metal ions (other than aluminum)or sources thereof are not added as an intentional ingredient to thereaction admixture that is used to synthesize the zeolite crystals, andthat if any alkali or alkaline earth metal ions are present in thezeolite, these metal ions are only present in an amount that isinconsequential to the intended catalytic activity of the zeolite.

JMZ-9 can contain less than about 0.1, preferably less than about 0.01,and more preferably less than about 0.001 weight percent of non-aluminummetal ions, based on the total weight of the zeolite.

JMZ-9 can contain less than about 0.1, preferably less than about 0.01,and more preferably less than about 0.001 weight percent of alkali metalions, based on the total weight of the zeolite.

JMZ-9 can contain less than about 0.1, preferably less than about 0.01,and more preferably less than about 0.001 weight percent of sodium metalions, based on the total weight of the zeolite.

JMZ-9 can contain less than about 0.1, preferably less than about 0.01,and more preferably less than about 0.001 weight percent ofalkaline-earth metal ions, based on the total weight of the zeolite.

JMZ-9 can contain less than about 0.1, preferably less than about 0.01,and more preferably less than about 0.001 weight percent of transitionmetal ions, based on the total weight of the zeolite.

JMZ-9 can contain less than about 0.1, preferably less than about 0.01,and more preferably less than about 0.001 weight percent of copper metalions, based on the total weight of the zeolite.

When used as a catalyst, JMZ-9 can include one or more post-synthesis,exchanged metals, typically in the form of metal ions and/or metaloxides. These post-synthesis exchanged metals are not part of thezeolite framework and are not present during zeolite synthesis (i.e.,crystal formation). Exchanged metals include: (a) noble metals, such asgold and silver; (b) platinum group metals, including platinum,palladium, rhodium, and ruthenium; (c) transition metals, such ascopper, iron, vanadium, manganese, and nickel; and (d) alkaline-earthmetals, such as calcium. Transition metals are preferred, with copperand iron being preferred transition metals.

The method of metal exchange is not necessarily limited, bution-exchange is a preferred method of loading metal onto the zeolite.Typically, a metal-exchanged JMZ-9 zeolite contains from about 0.1 toabout 7 weight percent of an exchanged metal based on the total weightof the zeolite, particularly when the exchanged metal is copper or iron.Other metal loading ranges include from about 1 to about 6 weightpercent, such as from about 2 to about 4 weight percent.

As used herein the terms “aluminosilicate zeolite” and “zeolite” areused interchangeably and mean a synthetic aluminosilicate molecularsieve having a framework constructed of alumina and silica (i.e.,repeating SiO₄ and AlO₄ tetrahedral units), and preferably having amolar silica-to-alumina ratio (SAR) of at least about 20, for exampleabout 22 to about 40.

The zeolites of the present invention are not silicoaluminophosphates(SAPOs) and thus do not have an appreciable amount of phosphorous intheir framework. That is, the zeolite frameworks do not have phosphorousas a regular repeating unit and/or do not have an amount of phosphorousthat would affect the basic physical and/or chemical properties of thematerial, particularly with respect to the material's capacity toselectively reduce NO_(x) over a broad temperature range. The amount offramework phosphorous can be less than 0.1 weight percent, preferablyless than 0.01 or more preferably less than 0.001 weight percent, basedon the total weight of the zeolite.

Zeolites, as used herein, are free or substantially free of frameworkmetals, other than aluminum. Thus, a “zeolite” and a “metal-exchangedzeolite” are distinct from a “metal-substituted zeolite” (also referredto as “isomorphous substituted zeolite”), wherein the latter comprises aframework that contains one or more non-aluminum metals substituted intothe zeolite's framework. Preferably, the JMZ-9 zeolite does not containframework non-aluminum transition metals in an appreciable amount, e.g.,less than about 10 ppm based on the total number of aluminum atoms inthe crystal framework. Any post-synthesis metal loaded on the zeolite ispreferably present as an ionic species within the interior channels andcavities of the zeolite framework.

In general, JMZ-9 zeolites are synthesized by preparing an admixturethat is essentially free of alkali metals (including alkali metal ions)and that contains at least one source of alumina, at least one source ofsilica, and at least one structure directing agent (SDA) in hydroxideform. The admixture can also contain water. The admixture is preferablyfree from additional sources of hydroxide ions. The admixture is treatedunder conditions to crystalize H-form zeolite crystals having an AEIframework with a template within the framework.

The SDA in hydroxide form is preferably present in relatively largeamounts compared to conventional synthesis techniques. For example, thesilica (SiO₂) and SDA are preferably present in the admixture in a molarratio of about 4:1 to about 1:1, preferably about 3:1 to about 1.5:1.Preferably, the molar ratio of silica-to-SDA and the molar ratio ofsilica-to-hydroxide is about the same, or at least within 10% of eachother. It has been unexpectedly found that at these high concentrations,the SDA in hydroxide form functions both as the templating agent and therole of an alkaline source. Accordingly, no other alkali sources areneeded. When alkali metal is eliminated from the admixture, theresulting AEI crystals are alkali-metal free.

The SDA(s) are selected for directing AEI synthesis. Examples ofsuitable SDAs include N,N-diethyl-cis-2,6-dimethylpiperidinium hydroxide(2,6-DMP) The anion associated with suitable SDA cations is hydroxide.Preferably, the reaction admixture and the resulting AEI zeolite areessentially free of non-hydroxide anions including halogen, e.g.,fluoride, chloride, bromide and iodide, as well as acetate, sulfate,nitrate, tetrafluoroborate, and carboxylate.

In certain examples of the invention, the reaction admixture comprises2,6-DMP as an SDA. The admixture can further comprise a second SDA.Preferably, the reaction admixture comprises at least about 20 weightpercent 2,6-DMP, such as about 20 to about 100 percent, about 20 toabout 50 percent, about 50 to about 100 percent, about 25 to about 75percent, about 75 to about 100 percent, or about 40 to about 60 percent,based on the total weight of the SDAs. The remaining material to make up100% of the weight of the SDA is a second SDA.

The reaction admixture can comprise a majority weight percent of 2,6-DMPbased on the total weight the SDAs.

The abovementioned 2,6-DMP ranges can be used in combination withN,N-Dimethyl-3,5-dimethylpiperidinium (3,5-DMP), and preferably, 3,5-DMPcomprises the balance of the SDAs.

The SDAs can comprise both 2,6-DMP and 3,5-DMP.

The SDAs can consist of (contain) only 2,6-DMP and 3,5-DMP.

At least about 20 weight percent 2,6-DMP can be used in combination withone or more intermediate hydrophobic templates (C/N⁺ ratio=8-12), suchas 3,5-DMP, trimethyl cyclohexylammonium (TMCHA), tetraethylammonium(TEA), Dimethyldipropylammonium (DMDPA), tetrapropylammonium (TPA),tetraethylphosphonium (TEP).

Silica sources resulting in a high relative yield (greater than about50%, greater than about 70%, greater than about 80%, or greater thanabout 90%) are preferred. Suitable silica sources include, withoutlimitation, synthetic faujasites, fumed silica, silicates, precipitatedsilica, colloidal silica, silica gels, dealuminated zeolites, siliconalkoxides, and silicon hydroxides. Particularly preferred are syntheticfaujasites such as zeolite Y. Preferred zeolite Y materials have asilica-to-alumina ratio (SAR) of about 10 to about 100, preferably about12 to about 60.

Methods of the present invention unexpectedly have a relative yield onsilica of greater than about 50%, greater than about 70%, greater thanabout 80%, or greater than about 90%. Inventors have found that thepresent synthesis methods result in a high relative yield on silica inan AEI zeolite synthesis process. As used herein, the term “relativeyield” with respect to a chemical reactant, means the amount of thereactant (or derivative thereof) that is incorporated into a desiredproduct as a fraction of the total amount of reactant introduced intothe chemical process. Thus, the relative yield of a reactant can becalculated as follows:

(Relative Yield) R=(R _(P))/(R _(T))

where R is the reactant, R_(P) is the total weight of reactant R (orderivative thereof) incorporated into the desired product, and R_(T) istotal weight of reactant R introduced into the chemical process. Here,the relative yield serves to measure the effectiveness of the chemicalprocess in utilizing the reactant. Here, “relative yield” is notsynonymous with the term “overall relative yield” which means therelative yield for a chemical process as a whole, including for example,multiple sequential zeolite synthesis batch reactions. Thus, the overallrelative yield on silica represents the total amount of silica that isincorporated into the total amount of zeolite produced across one ormore sequential batches (vis-à-vis the amount of silica remaining in adiscarded mother liquor) relative to the total amount of silicaintroduced into the process as a whole. The total amounts of thesematerials typically correspond to the material's total weight.

Typical alumina sources also are generally known and include syntheticfaujasites, aluminates, alumina, other zeolites, aluminum colloids,boehmites, pseudo-boehmites, aluminum hydroxides, aluminum salts such asaluminum sulfate and alumina chloride, aluminum hydroxides andalkoxides, alumina gels. Particularly preferred are synthetic faujasitessuch as zeolite Y. Preferred zeolite Y materials have asilica-to-alumina ratio (SAR) of about 10 to about 100, preferably about12 to about 60.

Preferably, the source of alumina and the source of silica are bothsynthetic faujasite (FAU). The synthetic faujasite may be single type ofFAU zeolite or a mixture of two or more FAU zeolites.

The H-AEI synthesis is preferably conducted by combining predeterminedrelative amounts of the silica source, aluminum source, the SDA(s), andother components, such as water, under various mixing and heatingregimens as will be readily apparent to those skilled in the art. Seedcrystals, such as AEI zeolite, can also be included in the admixture.JMZ-9 can be prepared from a reaction mixture having the compositionshown in Table 1 (shown as molar ratios). The reaction mixture can be inthe form of a solution, gel, or paste. Silicon- and aluminum-containingreactants are expressed as SiO₂ and Al₂)₃, respectively.

TABLE 1 Ratios Typical Preferred SiO₂/OH 1-4 1.5-2.5 SiO₂/SDA(s) 1-41.5-2.5 H₂O/SiO₂ 10-40 15-30 alkali metal/SiO₂ 0 0 Al₂O₃/SiO₂ 0.02-0.050.025-0.04 

Reaction temperatures, mixing times and speeds, and other processparameters that are suitable for conventional AEI synthesis techniquesare also generally suitable for the present invention. Withoutlimitation, the following synthesis steps can be followed to synthesizeJMZ-9. An aluminum source and a silica source (one or more zeolite Ymaterials, each with a SAR of about 10 to about 60) can be mixed inwater and combined with an organic templating agent (e.g.,1,1-Diethyl-2,6-dimethylpiperidinium). The components can be mixed bystirring or agitation until a homogeneous mixture is formed.Hydrothermal crystallization can be conducted under autogenous pressure,at a temperature of about 100 to 200° C. for a duration of several days,such about 1-20 days, preferably about 1-3 days.

At the conclusion the crystallization period, the resulting solids areseparated from the remaining reaction liquid by standard mechanicalseparation techniques, such as vacuum filtration. The recovered solidsare then rinsed with deionized water, and dried at an elevatedtemperature (e.g., 75-150° C.) for several hours (e.g., about 4 to 24hours). The drying step can be performed under vacuum or at atmosphericpressure.

The dried JMZ-9 crystals are preferably calcined, but can also be usedwithout calcination.

It will be appreciated that the foregoing sequence of steps, as well aseach of the above-mentioned periods of time and temperature values, aremerely exemplary and can be varied.

The JMZ-9 zeolite can be useful as a catalyst in certain applications,preferably with a post-synthesis metal exchange wherein one or morecatalytic metals is exchanged into the channels and/or cavities of thezeolite. Examples of metals that can be post-zeolite synthesis exchangedor impregnated include (a) transition metals, including copper, nickel,zinc, iron, tungsten, molybdenum, cobalt, titanium, zirconium,manganese, chromium, vanadium, niobium, tin, bismuth, and antimony; (b)noble metals including platinum group metals (PGMs), such as ruthenium,rhodium, palladium, indium, platinum, and precious metals such as goldand silver, (c) alkaline earth metals such as beryllium, magnesium,calcium, strontium, and barium; and (d) rare earth metals such aslanthanum, cerium, praseodymium, neodymium, europium, terbium, erbium,ytterbium, and yttrium. Preferred transition metals for post-synthesisexchange are base metals, and preferred base metals are those selectedfrom the group consisting of copper, iron, manganese, vanadium, nickel,and mixtures thereof. Metals incorporated post-synthesis can be added tothe molecular sieve via any known technique such as ion exchange,impregnation, isomorphous substitution, etc. The amount of metalpost-synthesis exchanged can be from about 0.1 to about 7 weightpercent, for example about 2 to about 5 weight percent, based on thetotal weight of the zeolite.

The metal-containing zeolite preferably contains post-synthesisexchanged alkaline earth metal, particularly calcium and/or magnesium,disposed within the channels and/or cavities of the zeolite framework.Thus, the metal-containing zeolite of the present invention can havetransition metals (T_(M)), such as copper or iron, incorporated into thezeolite channels and/or cavities during synthesis and have one or moreexchanged alkaline earth metals (A_(M)), such as calcium or potassium,incorporated post-synthesis. The alkaline earth metal can be present inan amount relative to the transition metal that is present. For example,T_(M) and A_(M) are preferably present, respectively, in a molar ratioof about 15:1 to about 1:1, about 10:1 to about 2:1, about 10:1 to about3:1, or about 6:1 to about 4:1, particularly were T_(M) is copper andA_(M) is calcium. Preferably, the relative cumulative amount oftransition metal (T_(M)) and alkaline earth metal (A_(M)) is present inthe zeolite material in an amount relative to the amount of aluminum inthe zeolite, namely the framework aluminum. As used herein, the(T_(M)+A_(M)):Al ratio is based on the relative molar amounts ofT_(M)+A_(M) to molar framework Al in the corresponding zeolite.Preferably, the catalyst material has a (T_(M)+A_(M)):Al ratio of notmore than about 0.6 or about 0.5 and can be from about 0.05 to about0.5, about 0.1 to about 0.4, or about 0.1 to about 0.2.

Preferably, Ce is impregnated post-synthesis into the JMZ-9, forexample, by adding Ce nitrate to a copper promoted zeolite via aconventional incipient wetness technique. Preferably, the cerium in thecatalyst material is present in a concentration of at least about 1weight percent, based on the total weight of the zeolite. Preferredconcentrations include at least about 2.5 weight percent, at least about5 weight percent, at least about 8 weight percent, at least about 10weight percent, about 1.35 to about 13.5 weight percent, about 2.7 toabout 13.5 weight percent, about 2.7 to about 8.1 weight percent, about2 to about 4 weight percent, about 2 to about 9.5 weight percent, andabout 5 to about 9.5 weight percent, based on the total weight of thezeolite.

Preferably, the cerium concentration in the catalyst material can beabout 50 to about 550 g/ft³, from about 75 to about 350 g/ft³, fromabout 100 to about 300 g/ft³, or from about 100 to about 250 g/ft³. Cecan be present at concentrations above 100 g/ft³, above 200 g/ft³, above300 g/ft³, above 400 g/ft³, or above 500 g/ft³.

The catalyst can be part of a washcoat composition, the washcoat canfurther comprise a binder containing Ce or ceria. Preferably, the Cecontaining particles in the binder are significantly larger than the Cecontaining particles in the catalyst.

Applicants further discovered that the foregoing synthesis procedurepermits adjusting the SAR of the catalyst based on the composition ofthe starting synthesis mixture. SARs of 10-50, 20-40, 30-40, 10-15, and25-35, for example, can be selectively achieved based on the compositionof the starting synthesis mixture and/or adjusting other processvariables. The SAR of zeolites can be determined by conventionalanalysis. This ratio is meant to represent, as closely as possible, theratio in the rigid atomic framework of the zeolite crystal and toexclude silicon or aluminum in the binder or, in cationic or other form,within the channels. It will be appreciated that it can be extremelydifficult to directly measure the SAR of zeolite after it has beencombined with a binder material. Accordingly, the SAR has been expressedhereinabove in term of the SAR of the parent zeolite, i.e., the zeoliteused to prepare the catalyst, as measured prior to the combination ofthis zeolite with the other catalyst components.

The foregoing synthesis procedure can result in zeolite crystals ofuniform size and shape with relatively low amounts of agglomeration. Inaddition, the synthesis procedure can result in zeolite crystals havinga mean crystalline size of about 0.2 to about 10 μm, about 0.5 to about5 μm, about 0.2 to about 1 μm, about 1 to about 5 μm, about 3 to about 7μm, and the like. Preferably, large crystals are milled using a jet millor other particle-on-particle milling technique to an average size ofabout 1.0 to about 1.5 micron to facilitate washcoating a slurrycontaining the catalyst to a substrate, such as a flow-through monolith.Alternatively, the crystals can be unmilled.

Crystal size is the length of one edge of a face of the crystal. Thecrystal size is based on individual crystals (including twinnedcrystals) but does not include agglomerations of crystals. Directmeasurement of the crystal size can be performed using microscopymethods, such as SEM and TEM. Other techniques for determining meanparticle size, such as laser diffraction and scattering can also beused.

In addition to the mean crystal size, catalyst compositions preferablyhave a majority of the crystal sizes are greater than about 0.2 μm,preferably between about 0.5 and about 5 μm, about 0.7 to about 5 μm,about 1 to about 5 μm, about 1.5 to about 5.0 μm, about 1.5 to about 4.0μm, about 2 to about 5 μm, or about 1 μm to about 10 μm.

Catalysts of the present invention are particularly applicable forheterogeneous catalytic reaction systems (i.e., solid catalyst incontact with a gas reactant). To improve contact surface area,mechanical stability, and/or fluid flow characteristics, the catalystscan be disposed on and/or within a substrate, preferably a poroussubstrate. Preferably, a washcoat containing the catalyst can be appliedto an inert substrate, such as corrugated metal plate or a honeycombcordierite brick. Alternatively, the catalyst can be kneaded along withother components such as fillers, binders, and reinforcing agents, intoan extrudable paste which is then extruded through a die to form ahoneycomb brick. Accordingly, in a catalyst article comprising a JMZ-9catalyst described herein can be coated on and/or incorporated into asubstrate.

Certain aspects of the invention provide a catalytic washcoat. Thewashcoat comprising the JMZ-9 catalyst described herein is preferably asolution, suspension, or slurry. Suitable coatings include surfacecoatings, coatings that penetrate a portion of the substrate, coatingsthat permeate the substrate, or some combination thereof.

A washcoat can also include non-catalytic components, such as fillers,binders, stabilizers, rheology modifiers, and other additives, includingone or more of alumina, silica, non-zeolite silica alumina, titania,zirconia, ceria. The catalyst composition may comprise pore-formingagents such as graphite, cellulose, starch, polyacrylate, andpolyethylene, and the like. These additional components do notnecessarily catalyze the desired reaction, but instead improve thecatalytic material's effectiveness, for example, by increasing itsoperating temperature range, increasing contact surface area of thecatalyst, increasing adherence of the catalyst to a substrate, etc.Preferably, the washcoat loading is >0.3 g/in³, >1.2 g/in³, >1.5g/in³, >1.7 g/in³ or >2.00 g/in³, and preferably <3.5 g/in³, or <2.5g/in³. The washcoat can be applied to a substrate at a loading of about0.8 to 1.0 g/in³, 1.0 to 1.5 g/in³, or 1.5 to 2.5 g/in³.

Two of the most common substrate designs are plate and honeycomb.Preferred substrates, particularly for mobile applications, includeflow-through monoliths having a so-called honeycomb geometry thatcomprise multiple adjacent, parallel channels that are open on both endsand generally extend from the inlet face to the outlet face of thesubstrate and result in a high-surface area-to-volume ratio. For certainapplications, the honeycomb flow-through monolith preferably has a highcell density, for example about 600 to 800 cells per square inch, and/oran average internal wall thickness of about 0.18-0.35 mm, preferablyabout 0.20-0.25 mm. For certain other applications, the honeycombflow-through monolith preferably has a low cell density of about 150-600cells per square inch, more preferably about 200-400 cells per squareinch. Preferably, the honeycomb monoliths are porous. In addition tocordierite, silicon carbide, silicon nitride, ceramic, and metal, othermaterials that can be used for the substrate include aluminum nitride,silicon nitride, aluminum titanate, α-alumina, mullite, e.g., acicularmullite, pollucite, a thermet such as Al₂OsZFe, Al₂O₃/Ni or B₄CZFe, orcomposites comprising segments of any two or more thereof. Preferredmaterials include cordierite, silicon carbide, and alumina titanate.

Plate-type catalysts have lower pressure drops and are less susceptibleto plugging and fouling than the honeycomb types, which is advantageousin high efficiency stationary applications, but plate configurations canbe much larger and more expensive. A honeycomb configuration istypically smaller than a plate type, which is an advantage in mobileapplications, but has higher pressure drops and plug more easily.Preferably, the plate substrate is constructed of metal, preferablycorrugated metal.

The invention is a catalyst article can be made by a process describedherein. Preferably, the catalyst article is produced by a process thatincludes the steps of applying a JMZ-9 catalyst composition, preferablyas a washcoat, to a substrate as a layer either before or after at leastone additional layer of another composition for treating exhaust gas hasbeen applied to the substrate. The one or more catalyst layers on thesubstrate, including the JMZ-9 catalyst layer, are arranged inconsecutive layers. As used herein, the term “consecutive” with respectto catalyst layers on a substrate means that each layer is contact withits adjacent layer(s) and that the catalyst layers as a whole arearranged one on top of another on the substrate.

The JMZ-9 catalyst can be disposed on the substrate as a first layer andanother composition, such as an oxidation catalyst, reduction catalyst,scavenging component, or NO_(x) storage component, can be disposed onthe substrate as a second layer. Alternatively, the JMZ-9 catalyst canbe disposed on the substrate as a second layer and another composition,such as such as an oxidation catalyst, reduction catalyst, scavengingcomponent, or NO_(x) storage component, is disposed on the substrate asa first layer. As used herein the terms “first layer” and “second layer”are used to describe the relative positions of catalyst layers in thecatalyst article with respect to the normal direction of exhaust gasflow-through, past, and/or over the catalyst article. Under normalexhaust gas flow conditions, exhaust gas contacts the first layer priorto contacting the second layer. The second layer can be applied to aninert substrate as a bottom layer and the first layer is top layer thatis applied over the second layer as a consecutive series of sub-layers.The exhaust gas can penetrate (and hence contacts) the first layer,before contacting the second layer, and subsequently returns through thefirst layer to exit the catalyst component. The first layer can be afirst zone disposed on an upstream portion of the substrate and thesecond layer is disposed on the substrate as a second zone, wherein thesecond zone is downstream of the first.

The catalyst article can be produced by a process that includes thesteps of applying a JMZ-9 catalyst composition, preferably as awashcoat, to a substrate as a first zone, and subsequently applying atleast one additional composition for treating an exhaust gas to thesubstrate as a second zone, wherein at least a portion of the first zoneis downstream of the second zone. Alternatively, the JMZ-9 catalystcomposition can be applied to the substrate in a second zone that isdownstream of a first zone containing the additional composition.Examples of additional compositions include oxidation catalysts,reduction catalysts, scavenging components (e.g., for sulfur, water,etc.), or NO_(x) storage components.

To reduce the amount of space required for an exhaust system, individualexhaust components can be designed to perform more than one function.For example, applying an SCR catalyst to a wall-flow filter substrateinstead of a flow-through substrate serves to reduce the overall size ofan exhaust treatment system by allowing one substrate to serve twofunctions, namely catalytically reducing NOx concentration in theexhaust gas and mechanically removing soot from the exhaust gas.Accordingly, the substrate can be a honeycomb wall-flow filter orpartial filter. Wall-flow filters are similar to flow-through honeycombsubstrates in that they contain a plurality of adjacent, parallelchannels. However, the channels of flow-through honeycomb substrates areopen at both ends, whereas the channels of wall-flow substrates have oneend capped, wherein the capping occurs on opposite ends of adjacentchannels in an alternating pattern. Capping alternating ends of channelsprevents the gas entering the inlet face of the substrate from flowingstraight through the channel and existing. Instead, the exhaust gasenters the front of the substrate and travels into about half of thechannels where it is forced through the channel walls prior to enteringthe second half of the channels and exiting the back face of thesubstrate.

The substrate wall has a porosity and pore size that is gas permeable,but traps a major portion of the particulate matter, such as soot, fromthe gas as the gas passes through the wall. Preferred wall-flowsubstrates are high efficiency filters. Wall flow filters for use withthe present invention preferably have an efficiency of least 70%, atleast about 75%, at least about 80%, or at least about 90%. Theefficiency can be in a range from about 75 to about 99%, about 75 toabout 90%, about 80 to about 90%, or about 85 to about 95%. Here,efficiency is relative to soot and other similarly sized particles andto particulate concentrations typically found in conventional dieselexhaust gas. For example, particulates in diesel exhaust can range insize from 0.05 microns to 2.5 microns. Thus, the efficiency can be basedon this range or a sub-range, such as 0.1 to 0.25 microns, 0.25 to 1.25microns, or 1.25 to 2.5 microns.

Porosity is a measure of the percentage of void space in a poroussubstrate and is related to backpressure in an exhaust system:generally, the lower the porosity, the higher the backpressure.Preferably, the porous substrate has a porosity of about 30 to about80%, for example about 40 to about 75%, about 40 to about 65%, or fromabout 50 to about 60%.

The pore interconnectivity, measured as a percentage of the substrate'stotal void volume, is the degree to which pores, void, and/or channels,are joined to form continuous paths through a porous substrate, i.e.,from the inlet face to the outlet face. In contrast to poreinterconnectivity is the sum of closed pore volume and the volume ofpores that have a conduit to only one of the surfaces of the substrate.Preferably, the porous substrate has a pore interconnectivity volume ofat least about 30%, more preferably at least about 40%.

The mean pore size of the porous substrate is also important forfiltration. Mean pore size can be determined by any acceptable means,including by mercury porosimetry. The mean pore size of the poroussubstrate should be of a high enough value to promote low backpressure,while providing an adequate efficiency by either the substrate per se,by promotion of a soot cake layer on the surface of the substrate, orcombination of both. Preferred porous substrates have a mean pore sizeof about 10 to about 40 μm, for example about 20 to about 30 μm, about10 to about 25 μm, about 10 to about 20 μm, about 20 to about 25 μm,about 10 to about 15 μm, and about 15 to about 20 μm.

In general, the production of an extruded solid body containing theJMZ-9 catalyst involves blending the JMZ-9 catalyst, a binder, anoptional organic viscosity-enhancing compound into a homogeneous pastewhich is then added to a binder/matrix component or a precursor thereofand optionally one or more of stabilized ceria, and inorganic fibers.The blend is compacted in a mixing or kneading apparatus or an extruder.The mixtures have organic additives such as binders, pore formers,plasticizers, surfactants, lubricants, dispersants as processing aids toenhance wetting and therefore produce a uniform batch. The resultingplastic material is then molded, in particular using an extrusion pressor an extruder including an extrusion die, and the resulting moldingsare dried and calcined. The organic additives are “burnt out” duringcalcinations of the extruded solid body. A JMZ-9 catalyst can also bewashcoated or otherwise applied to the extruded solid body as one ormore sub-layers that reside on the surface or penetrate wholly or partlyinto the extruded solid body.

Extruded solid bodies containing JMZ-9 catalysts according to thepresent invention generally comprise a unitary structure in the form ofa honeycomb having uniform-sized and parallel channels extending from afirst end to a second end thereof. Channel walls defining the channelsare porous. Typically, an external “skin” surrounds a plurality of thechannels of the extruded solid body. The extruded solid body can beformed from any desired cross section, such as circular, square or oval.Individual channels in the plurality of channels can be square,triangular, hexagonal, circular etc. Channels at a first, upstream endcan be blocked, e.g. with a suitable ceramic cement, and channels notblocked at the first, upstream end can also be blocked at a second,downstream end to form a wall-flow filter. Typically, the arrangement ofthe blocked channels at the first, upstream end resembles achecker-board with a similar arrangement of blocked and open downstreamchannel ends.

The binder/matrix component is preferably selected from the groupconsisting of cordierite, nitrides, carbides, borides, intermetallics,lithium aluminosilicate, a spinel, an optionally doped alumina, a silicasource, titania, zirconia, titania-zirconia, zircon and mixtures of anytwo or more thereof. The paste can optionally contain reinforcinginorganic fibers selected from the group consisting of carbon fibers,glass fibers, metal fibers, boron fibers, alumina fibers, silica fibers,silica-alumina fibers, silicon carbide fibers, potassium titanatefibers, aluminum borate fibers and ceramic fibers.

The alumina binder/matrix component is preferably gamma alumina, but canbe any other transition alumina, i.e., alpha alumina, beta alumina, chialumina, eta alumina, rho alumina, kappa alumina, theta alumina, deltaalumina, lanthanum beta alumina and mixtures of any two or more suchtransition aluminas. It is preferred that the alumina is doped with atleast one non-aluminum element to increase the thermal stability of thealumina. Suitable alumina dopants include silicon, zirconium, barium,lanthanides and mixtures of any two or more thereof. Suitable lanthanidedopants include La, Ce, Nd, Pr, Gd and mixtures of any two or morethereof.

Sources of silica can include a silica sol, quartz, fused or amorphoussilica, sodium silicate, an amorphous aluminosilicate, an alkoxysilane,a silicone resin binder such as methylphenyl silicone resin, a clay,talc or a mixture of any two or more thereof. Of this list, the silicacan be SiO₂ as such, feldspar, mullite, silica-alumina, silica-magnesia,silica-zirconia, silica-thoria, silica-berylia, silica-titania, ternarysilica-alumina-zirconia, ternary silica-alumina-magnesia,temary-silica-magnesia-zirconia, temary silica-alumina-thoria andmixtures of any two or more thereof.

Preferably, the JMZ-9 catalyst is dispersed throughout, and preferablyevenly throughout, the entire extruded catalyst body.

Where any of the above extruded solid bodies are made into a wall-flowfilter, the porosity of the wall-flow filter can be from 30-80%, such asfrom 40-70%. Porosity and pore volume and pore radius can be measurede.g. using mercury intrusion porosimetry.

The JMZ-9 catalyst described herein can promote the reaction of areductant, preferably ammonia, with nitrogen oxides to selectively formelemental nitrogen (N₂) and water (H₂O). Thus, the catalyst can beformulated to favor the reduction of nitrogen oxides with a reductant(i.e., an SCR catalyst). Examples of such reductants includehydrocarbons (e.g., C3-C6 hydrocarbons) and nitrogenous reductants suchas ammonia and ammonia hydrazine or any suitable ammonia precursor, suchas urea ((NH₂)₂CO), ammonium carbonate, ammonium carbamate, ammoniumhydrogen carbonate or ammonium formate.

The JMZ-9 catalyst described herein can also promote the oxidation ofammonia. Thus, the catalyst can be formulated to favor the oxidation ofammonia with oxygen, particularly a concentrations of ammonia typicallyencountered downstream of an SCR catalyst (e.g., ammonia oxidation(AMOX) catalyst, such as an ammonia slip catalyst (ASC)). The JMZ-9catalyst can be disposed as a top layer over an oxidative under-layer,wherein the under-layer comprises a platinum group metal (PGM) catalystor a non-PGM catalyst. Preferably, the catalyst component in theunderlayer is disposed on a high surface area support, including but notlimited to alumina.

An SCR and AMOX operations can be performed in series, wherein bothprocesses utilize a catalyst comprising the JMZ-9 catalyst describedherein, and wherein the SCR process occurs upstream of the AMOX process.For example, an SCR formulation of the catalyst can be disposed on theinlet side of a filter and an AMOX formulation of the catalyst can bedisposed on the outlet side of the filter.

Accordingly, provided is a method for the reduction of NO_(x) compoundsor oxidation of NH₃ in a gas, which comprises contacting the gas with acatalyst composition described herein for the catalytic reduction ofNO_(x) compounds for a time sufficient to reduce the level of NO_(x)compounds and/or NH₃ in the gas. Also provided is a catalyst articlehaving an ammonia slip catalyst disposed downstream of a selectivecatalytic reduction (SCR) catalyst. The ammonia slip catalyst canoxidize at least a portion of any nitrogenous reductant that is notconsumed by the selective catalytic reduction process. For example, theammonia slip catalyst can be disposed on the outlet side of a wall flowfilter and an SCR catalyst is disposed on the upstream side of a filter.The ammonia slip catalyst can be disposed on the downstream end of aflow-through substrate and an SCR catalyst is disposed on the upstreamend of the flow-through substrate. The ammonia slip catalyst and SCRcatalyst can be disposed on separate bricks within the exhaust system.These separate bricks can be adjacent to, and in contact with, eachother or separated by a specific distance, provided that they are influid communication with each other and provided that the SCR catalystbrick is disposed upstream of the ammonia slip catalyst brick.

The SCR and/or AMOX process can be performed at a temperature of atleast 100° C. The process(es) can occur at a temperature from about 150°C. to about 750° C. Preferably the temperature range is from about 175to about 550° C. or from about 175 to about 400° C. Alternatively, thetemperature range is about 450 to about 900° C., preferably about 500 toabout 750° C., about 500 to about 650° C., about 450 to about 550° C.,or about 650 to about 850° C. Temperatures greater than about 450° C.are particularly useful for treating exhaust gases from a heavy or lightduty diesel engine that is equipped with an exhaust system comprising(optionally catalyzed) diesel particulate filters which are regeneratedactively, e.g. by injecting hydrocarbon into the exhaust system upstreamof the filter, wherein the zeolite catalyst for use in the presentinvention is located downstream of the filter.

According to another aspect of the invention, provided is a method forthe reduction of NO_(X) compounds and/or oxidation of NH₃ in an exhaustgas, which comprises contacting the exhaust gas with a catalystdescribed herein in the presence of a reducing agent for a timesufficient to reduce the level of NO_(X) compounds in the gas. Thesemethods can further comprise one or more of the following steps: (a)accumulating and/or combusting soot that is in contact with the inlet ofa catalytic filter; (b) introducing a nitrogenous reducing agent intothe exhaust gas stream prior to contacting the catalyst in an SCRfilter, preferably with no intervening catalytic steps involving thetreatment of NO_(x) and the reductant; (c) generating NH₃ over a NO_(x)adsorber catalyst or lean NO_(x) trap, and preferably using such NH₃ asa reductant in a downstream SCR reaction; (d) contacting the exhaust gasstream with a DOC to oxidize hydrocarbon based soluble organic fraction(SOF) and/or carbon monoxide into CO₂, and/or oxidize NO into NO₂,which, in turn, can be used to oxidize particulate matter in particulatefilter; and/or reduce the particulate matter (PM) in the exhaust gas;and (e) contacting the exhaust gas with an ammonia slip catalyst,preferably downstream of the SCR catalyst to oxidize most, if not all,of the ammonia prior to emitting the exhaust gas into the atmosphere orpassing the exhaust gas through a recirculation loop prior to exhaustgas entering/re-entering the engine.

All or at least a portion of the nitrogen-based reductant, particularlyNH₃, for consumption in the SCR process can be supplied by a NO_(X)adsorber catalyst (NAC), a lean NO_(X) trap (LNT), or a NO_(X)storage/reduction catalyst (NSRC), disposed upstream of the SCRcatalyst, e.g., a SCR catalyst of the present invention disposed on awall-flow filter. NAC components useful in the present invention includea catalyst combination of a basic material (such as alkali metal,alkaline earth metal or a rare earth metal, including oxides of alkalimetals, oxides of alkaline earth metals, and combinations thereof), anda precious metal (such as platinum), and optionally a reduction catalystcomponent, such as rhodium. Specific types of basic material useful inthe NAC include cesium oxide, potassium oxide, magnesium oxide, sodiumoxide, calcium oxide, strontium oxide, barium oxide, and combinationsthereof. The precious metal is preferably present at about 10 to about200 g/ft³, such as 20 to 60 g/ft³. Alternatively, the precious metal ofthe catalyst can have an average concentration from about 40 to about100 grams/ft³.

Under certain conditions, during the periodically rich regenerationevents, NH₃ can be generated over a NOx adsorber catalyst. The SCRcatalyst downstream of the NO_(x) adsorber catalyst can improve theoverall system NO_(x) reduction efficiency. In the combined system, theSCR catalyst is capable of storing the released NH₃ from the NACcatalyst during rich regeneration events and utilizes the stored NH₃ toselectively reduce some or all of the NO_(x) that slips through the NACcatalyst during the normal lean operation conditions.

The method for treating exhaust gas as described herein can be performedon an exhaust gas derived from a combustion process, such as from aninternal combustion engine (whether mobile or stationary), a gas turbineand coal or oil fired power plants. These methods may also be used totreat gas from industrial processes such as refining, from refineryheaters and boilers, furnaces, the chemical processing industry, cokeovens, municipal waste plants and incinerators, etc. The method can beused for treating exhaust gas from a vehicular lean burn internalcombustion engine, such as a diesel engine, a lean-burn gasoline engineor an engine powered by liquid petroleum gas or natural gas.

In certain aspects, the invention is a system for treating exhaust gasgenerated by combustion process, such as from an internal combustionengine (whether mobile or stationary), a gas turbine, coal or oil firedpower plants, and the like. Such systems include a catalytic articlecomprising the JMZ-9 catalyst described herein and at least oneadditional component for treating the exhaust gas, wherein the catalyticarticle and at least one additional component are designed to functionas a coherent unit.

The system can comprise a catalytic article comprising a JMZ-9 catalystdescribed herein, a conduit for directing a flowing exhaust gas, asource of nitrogenous reductant disposed upstream of the catalyticarticle. The system can include a controller for the metering thenitrogenous reductant into the flowing exhaust gas only when it isdetermined that the zeolite catalyst is capable of catalyzing NOxreduction at or above a desired efficiency, such as at above 100° C.,above 150° C. or above 175° C. The metering of the nitrogenous reductantcan be arranged such that 60% to 200% of theoretical ammonia is presentin exhaust gas entering the SCR catalyst calculated at 1:1 NH₃/NO and4:3 NH₃/NO₂.

The system can comprise an oxidation catalyst (e.g., a diesel oxidationcatalyst (DOC)) for oxidizing nitrogen monoxide in the exhaust gas tonitrogen dioxide can be located upstream of a point of metering thenitrogenous reductant into the exhaust gas. The oxidation catalyst canbe adapted to yield a gas stream entering the SCR zeolite catalysthaving a ratio of NO to NO₂ of from about 4:1 to about 1:3 by volume,e.g. at an exhaust gas temperature at oxidation catalyst inlet of 250°C. to 450° C. The oxidation catalyst can comprise at least one platinumgroup metal, such as platinum, palladium, or rhodium, or combinationsthereof, coated on a flow-through monolith substrate. The at least oneplatinum group metal can be platinum, palladium or a combination of bothplatinum and palladium. The platinum group metal can be supported on ahigh surface area washcoat component such as alumina, a zeolite such asan aluminosilicate zeolite, silica, non-zeolite silica alumina, ceria,zirconia, titania or a mixed or composite oxide containing both ceriaand zirconia.

A suitable filter substrate can be located between the oxidationcatalyst and the SCR catalyst. Filter substrates can be selected fromany of those mentioned above, e.g. wall flow filters. Where the filteris catalyzed, e.g. with an oxidation catalyst of the kind discussedabove, preferably the point of metering nitrogenous reductant is locatedbetween the filter and the zeolite catalyst. Alternatively, if thefilter is un-catalyzed, the means for metering nitrogenous reductant canbe located between the oxidation catalyst and the filter.

The metal-promoted small pore JMZ-9 zeolite catalyst described hereincan also be a passive NOx absorber (PNA) catalyst (i.e. it has PNAactivity). Such catalyst can be prepared according to the methoddescribed in WO 2012/166868 (also published as U.S. 2012308439) (both ofwhich are hereby incorporated by reference.), and the promoter metal cancomprise a noble metal.

When the noble metal comprises, or consists of, palladium (Pd) and asecond metal, then the ratio by mass of palladium (Pd) to the secondmetal is >1:1. More preferably, the ratio by mass of palladium (Pd) tothe second metal is >1:1 and the molar ratio of palladium (Pd) to thesecond metal is >1:1. The aforementioned ratio of palladium relates tothe amount of palladium present as part of the PNA catalyst. It does notinclude any palladium that may be present on the support material. ThePNA catalyst may further comprise a base metal. Thus, the PNA catalystmay comprise, or consist essentially of, a noble metal, a small porezeolite as described herein and optionally a base metal.

The base metal can be selected from the group consisting of iron (Fe),copper (Cu), manganese (Mn), chromium (Cr), cobalt (Co), nickel (Ni),zinc (Zn) and tin (Sn), as well as mixtures of two or more thereof. Itis preferred that the base metal is selected from the group consistingof iron, copper and cobalt, more preferably iron and copper. Even morepreferably, the base metal is iron.

Alternatively, the PNA catalyst can be substantially free of a basemetal, such as a base metal selected from the group consisting of iron(Fe), copper (Cu), manganese (Mn), chromium (Cr), cobalt (Co), nickel(Ni), zinc (Zn) and tin (Sn), as well as mixtures of two or morethereof. Thus, the PNA catalyst may not comprise a base metal.

In general, it is preferred that the PNA catalyst does not comprise abase metal.

It can be preferable that the PNA catalyst is substantially free ofbarium (Ba), more preferably the PNA catalyst is substantially free ofan alkaline earth metal. Thus, the PNA catalyst may not comprise barium,preferably the PNA catalyst does not comprise an alkaline earth metal.

Turning to FIG. 6, shown is an SCR and/or ASC catalyst 10, an exhaustgas 20, a purified gas 22, and a direction of flow through the SCRand/or ASC catalyst 30. The exhaust gas 20 has an inlet concentration ofNO and/or NO₂ and the purified gas 22 has an outlet concentration of NOand/or NO₂ that is less than the inlet concentration. The purified gas22 also has an outlet concentration of N20 that is less than the inletconcentration of NO and/or NO₂.

Although the description above contains many specifics, these are merelyprovided to illustrate the invention and should not be constructed aslimitations of the invention's scope. It should be also noted that manyspecifics could be combined in various ways in a single or multipleembodiments. Thus it will be apparent to those skilled in the art thatvarious modifications and variations can be made in the processes,catalysts, and methods of the present invention without departing fromthe spirit or scope of the invention.

EXAMPLES

Materials produced in the examples described below were characterized byone or more of the following analytic methods. Powder X-ray diffraction(PXRD) patterns were collected Bruker D8 powder diffractometer using aCuKα radiation (40 kV, 40 mA) at a step size of 0.02° and a 1 s per stepbetween 5° and 50° (2θ). Scanning electron microscopy (SEM) images andchemical compositions by energy-dispersive X-ray spectroscopy (EDX) wereobtained on an Auriga 60 CrossBeam (FIB/FE-SEM) microscope, operating atan acceleration voltage of 1.5-3 keV, and a current of 10 μA. Themicropore volume and surface area were measured using N₂ at 77 K on aMicrometrics 3Flex surface characterization analyzer.

Reagents:

Zeolite Y [CBV712 (SAR˜12), CBV720 (SAR˜30-32) from Zeolyst], DI water,N,N-diethyl-cis 2,6-dimethylpiperidium hydroxide (2,6-DMP-OH, 22% wt),N,N-dimethyl-3,5-dimethylpiperidium (34% wt), tetrapropylammonium (TPA,40% wt), Triethylenetetramine (TETA, Sigma), CuSO₄.5H₂O (Sigma).

Example 1: Preparation of H-AEI Zeolite Using 2,6-DMP as the SDA

13.69 g of 2,6-DMP-OH was mixed with 3.1 g of water. Then, the solutionwas stirred for about 5 minutes. Finally, 2.16 g of zeolite Y (CBV 720)as both aluminum and silica sources were added under stirring foranother 5 minutes. The final gel mixture having molar compositions of 25H₂O:1 SiO₂:0.033 Al₂O₃:0.5 2,6-DMP-OH was heated and rotated (45 rpm for23 ml reactor) at 155° C. for 5 days.

To obtain the AEI powder product, the autoclaves were cooled to roomtemperature in air and the crystalline product was recovered byfiltration, washed several times with deionized water and dried at 80°C. overnight in a drying oven. The as-made product (JMZ-9) was calcinedat 580° C./8 hours in air with ramping rate of 3° C./min. Samples of thedried product were analysed by XRD and SEM as described above. Analysisof the calcined product by powder XRD (FIG. 1) indicated that theproduct had an AEI structure. An SEM (FIG. 2a ) of the calcined productshowed that the material has cuboid morphology with crystal size ofabout 0.2 to about 0.5 micron. N₂ adsorption measurements of thecalcined product showed that the product had a BET surfaces area of ˜680m²/g, a pore volume of ˜0.27 cm³/g, and had a cubic morphology. Thecalcined product had an SAR of about 30.

Example 2: Preparation of H-AEI Zeolite Using 2,6-DMP as the SDA and aMixture of Faujasite Zeolites as Both Si and Al Sources

13.69 g of 2,6-DMP-OH was mixed with 3.1 g of water. Then, the solutionwas stirred for about 5 minutes. Finally, a mixture of 0.45 g zeolite Y(CBV712) and 1.72 g of zeolite Y (CBV 720) as both aluminum and silicasources was added under stirring for another 5 minutes. The reaction washeated and rotated (45 rpm for 23 ml reactor) at 155° C. for 5 days. Toobtain the AEI powder product, the autoclaves were cooled to roomtemperature in air and the crystalline product was recovered byfiltration, washed several times with deionized water and dried at 80°C. overnight in a drying oven. The as-made product (JMZ-9) was calcinedat 580° C./8 hours in air with ramping rate of 3° C./min. Samples of thedried product were analysed by XRD and SEM as described above. Analysisof the as made product by powder XRD indicated that the product had anAEI structure. An SEM of the calcined product showed that the materialhas cuboid morphology with crystal size of about 0.2 to about 0.5 micron(FIG. 2b ). The calcined product had an SAR of about 24. N₂ adsorptionmeasurements of the calcined product showed that the product had a porevolume of ˜0.28 cm³/g.

Example 3: Preparation of H-AEI Zeolite Using a Mixture of 2,6-DMP-OHand 3,5-DMP-OH as the SDAs

H-AEI (SAR≈30) was prepared by a similar method as described in Example1, in which 3,5-DMP was used as the co-template. The final gel withmolar composition ofH₂O:SiO2:Al₂O₃:2,6-DMP-OH:3,5-DMP-OH=25:1:0.033:0.25:0.2 was rotated inthe oven at 155° C. for 5 days. Analysis of the as made product bypowder XRD indicated that the product had a AEI structure, and thesample has rectangular parallelepiped morphology (SEM image as shown inFIG. 3).

Example 4: Preparation of H-AEI Zeolite Using a Mixture of 2,6-DMP-OHand TPA-OH as the SDAs

H-AEI (SAR≈30) was prepared by a similar method as described in Example1, in which TPA-OH was used as the co-template. The final gel with molarcomposition of H₂O:SiO2:Al₂O₃:2,6-DMP-OH:TPA-OH=25:1:0.033:0.25:0.2 wasrotated in the oven at 155° C. for 5 days. Analysis of the as madeproduct by powder XRD indicated that the product had a AEI structure,and the sample has the particle morphology as shown in FIG. 4.

Example 5: Preparation of Alkali-Free One-Pot Cu-AEI Zeolite Using aMixture of 2,6-DMP-OH and Cu(TETA)²⁺ as the SDAs

One pot Cu-AEI was prepared by a similar method as described in Example1, in which Cu(TETA)²⁺ was used as the co-template and copper source,CBV712 and CBV720 were used as both Si and Al sources. The final gelwith molar composition ofH₂O:SiO2:Al₂O₃:2,6-DMP-OH:Cu(TETA)²⁺=25:1:0.038:0.45:0.025 was rotatedin the oven at 155° C. for 5 days. Analysis of the as-made product bypowder XRD indicated that the product had a AEI structure.

Example 6: SCR Testing on Copper Exchanged Zeolite Catalysts

Synthesis of Copper Exchanged AEI:

˜2.5-3% wt of copper exchanged into the calcined prepared byconventional route AEI (SAR≈20), and H-AEI zeolite (SAR≈30, example 1)using Cu(CH₃COO)₂.

Testing Conditions:

SV=90K, 500 ppm NH₃, 500 ppm NO, 4.6% H₂O, 14%O₂, 5% CO₂ in N₂. Ramp 5°C./min.

Procedures:

Catalyst was initially exposed to full gas mixture with NH₃ for 10 minat 150° C. NH₃ was switched on and the catalyst is stabilized for 30 minto saturate. Catalyst was then evaluated during a 5° C./min ramp from150 to 500° C. Catalyst was evaluated at steady state at 500° C. thencooled and evaluated again at steady state at 250° C.

FIG. 5a shows NOx conversions on 3% Cu.AEI (SAR≈20) and Cu.H-AEI(SAR≈30, H-AEI from Example 1), with ˜2.5% wt of copper exchanged intothe AEI zeolites.

FIG. 5b shows N₂O selectivity of reference 3% Cu.AEI (SAR≈20) and 2.5%Cu.H-AEI (SAR≈30, H-AEI from Example 1) of the present invention. Highsilica Cu.AEI (SAR≈30) of the present invention demonstrated similarfresh SCR activities as lower silica Cu.AEI (SAR≈20) even with slightlylower Cu loading, and it showed some advantages on the N₂O selectivityover the catalyst from the reference AEI (SAR≈20). Catalyst 2.5%Cu.H-AEI also showed excellent hydrothermal durability after aging at900° C./5 h/4.5% H₂O.

FIG. 5c shows NO_(X) conversions on reference 3% Cu.AEI (SAR≈20) andone-pot Cu-AEI (Example 5).

FIG. 5d shows N₂O selectivity of reference 3% Cu.AEI (SAR≈20) andone-pot Cu-AEI (Example 5).

Alkali-free one-pot Cu-AEI of the present invention demonstrated similarfresh SCR activities as the reference Cu.AEI (SAR≈20), and it showedhigh advantages on the N₂O selectivity over the catalyst from thereference AEI (SAR≈20).

The above examples are set forth to aid in the understanding of thedisclosure, and are not intended and should not be construed to limit inany way the disclosure set forth in the claims which follow hereafter.Although illustrated and herein described with reference to certainspecific embodiments, the present disclosure is nevertheless notintended to be limited to the details shown, but various modificationsmay be made therein without departing from the spirit of the disclosure.

What is claimed is:
 1. A composition comprising a synthetichydrogen-form zeolite having an AEI framework as the primary crystallinephase and a structure directing agent (SDA) in hydroxide form, whereinsaid zeolite is essentially free of sodium ions.
 2. The composition ofclaim 1, wherein the composition is essentially free of alkali metal. 3.The composition of claim 1, wherein the zeolite is essentially free ofnon-aluminum metal ions.
 4. The composition of claim 1, wherein thezeolite has a silica-to-alumina ratio of about 22 to about
 50. 5. Amethod of synthesizing a zeolite comprising the steps of: a. preparingan admixture containing (i) at least one source of alumina, (ii) atleast one source of silica, and (iii) at least one structure directingagent (SDA) in hydroxide form, wherein the admixture is essentially freeof alkali metals; b. heating the admixture under autogenous pressure ata temperature and with stirring or mixing for a sufficient time tocrystalize hydrogen-form zeolite crystals having an AEI framework. 6.The method of claim 5, wherein the admixture is essentially free ofmetal ions, other than aluminum.
 7. The method of claim 5, wherein themolar ratio of SDA to silica is greater than 0.4:1.
 8. The method ofclaim 5, wherein the yield on silica is at least about 50%.
 9. Themethod of claim 5, wherein the sources of silica and alumina arefaujasite zeolites.
 10. The method of claim 5, wherein the at least oneSDA is N,N-diethyl-2,6-dimethylpiperidinium.
 11. The method of claim 10,further comprising a second SDA.
 12. The method of claim 11, wherein thesecond SDA is selected from 3,5-DMP, trimethyl cyclohexylammonium(TMCHA), tetraethylammonium (TEA), Dimethyldipropylammonium (DMDPA),tetrapropylammonium (TPA), tetraethylphosphonium (TEP).
 13. The methodof claim 11, wherein the second SDA isN,N-Dimethyl-3,5-dimethylpiperidinium
 14. A catalyst compositioncomprising a synthetic zeolite having an AEI framework as the primarycrystalline phase and a silica-to-alumina ratio of about 22 to about 50,wherein the zeolite has 0.1 to 7 weight percent exchanged transitionmetal and wherein the zeolite is essentially free of alkali metal. 15.The catalyst composition of claim 14, wherein the transition metal iscopper.
 16. The catalyst composition of claim 14, wherein the transitionmetal is iron.
 17. A catalyst article for treating exhaust gascomprising a catalyst composition according to claim 1 disposed onand/or within a honeycomb monolith substrate.
 18. A method for treatingan exhaust gas comprising contacting a combustion exhaust gas containingNO_(x) and/or NH₃ with a catalyst article according to claim 17 toselectively reduce at least a portion of the NO_(x) into N₂ and H₂Oand/or oxidize at least a portion of the NH₃.